A small white round pill with M on 1 side & C 34 on the other is Carvedilol 25mg, used to treat high blood pressure, heart failure, angina & more. A white capsule-shaped pill with imprint C 34 & no other markings is Sumatriptan Succinate 100mg, used to treat migraines. Always consult with a pharmacist or health professional before taking medication. Take only as directed. Any comments?